The present invention relates to a remote control system for remotely controlling various electronic devices, and more particularly to a remote control system for remotely controlling devices such as AV (audio visual) devices by way of voice commands.
In recent years, various AV devices such as stereo sets, television receivers, cassette tape decks, video tape decks, compact disk players, laser vision disk players, or the like are equipped with remote control systems.
A remote control system has a transmitter which is usually positioned remotely from a controlled AV device. The transmitter, when operated, transmits a remote control signal, such as an infrared remote control signal, which is received by a receiver in the controlled AV device. The received remote control signal is decoded to control the AV device as intended by the remote control signal.
There has recently been developed a voice-operated remote control system which employs voice control commands instead of control commands entered through keys. The voice-operated remote control system has a microphone mounted on a transmitter for converting a voice command into an electric voice signal, and a speech recognition LSI (Large Scale Integration) circuit for generating a remote control signal which corresponds to a voice pattern represented by the voice signal. The remote control signal thus generated is transmitted to a receiver in a controlled AV device.
In the transmitter of the voice-operated remote control system, a power supply circuit supplies electric energy to the speech recognition LSI circuit, a controller, and other components. In order to process voice commands which may be applied all of a sudden, the speech recognition LSI circuit is normally kept in a standby condition, i.e., remains energized at all times.
If the speech recognition LSI circuit remains energized at all times, then it can also receive other voices than the voices of the operator. As a result, while the AV device is being operated to reproduce recorded sounds, voice signals contained in the reproduced sounds may be entered through the microphone, and the input voice signals may be recognized in error as voice commands, causing an erroneous operation of the AV device.
The speech recognition LSI circuit has a higher power requirement than the usual remote control LSI circuits. Therefore, if the transmitter is battery-powered, it may easily malfunction due to a quick voltage drop resulting from the power consumption by the speech recognition LSI circuit.
A transmitter which incorporates a conventional voice-operated remote control system transmits a remote control signal indicative of a control command only when a voice command is received. When it is desired to repeat one control mode such as for a continuous increase in an audio output power, a voice command for such control mode must be repeated. Such a repeated entry of the same voice command is however inconvenient and tedious.